Optical system

ABSTRACT

An optical system includes a first lens including a negative refractive power and a convex object-side surface, a second lens, and a third lens including a negative refractive power and a convex object-side surface. The optical system also includes a fourth lens, a fifth lens including a negative refractive power, and a sixth lens including a negative refractive power and comprising an inflection point on an image-side surface thereof. The first to sixth lenses are sequentially disposed from an object toward an imaging plane.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority and benefit of Korean PatentApplication No. 10-2015-0112495, filed on Aug. 10, 2015 with the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference.

BACKGROUND 1. Field

The following description relates to an optical system including lenseshaving refractive power.

2. Description of Related Art

Over the years, camera modules have gradually been miniaturized. Inaddition, camera module performance has gradually improved. As anexample, pixels of an image sensor have become small enough to enablerealization of high resolution.

Typically, an optical system of a small camera module includes fourlenses. However, it is difficult for the optical system including thefour lenses to implement a clear image. Therefore, development of anoptical system including five or more lenses is needed in order toenable realization of a clear image.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In accordance with an embodiment, there is provided an optical system,including: a first lens including a negative refractive power and aconvex object-side surface; a second lens; a third lens including anegative refractive power and a convex object-side surface; a fourthlens; a fifth lens including a negative refractive power; and a sixthlens including a negative refractive power and including an inflectionpoint on an image-side surface thereof, wherein the first to sixthlenses are sequentially disposed from an object toward an imaging plane.

V1, an Abbe number of the first lens and, V3, an Abbe number of thethird lens may satisfy 25<V1−V3<45.

f, an overall focal length of the optical system and, f2, a focal lengthof the second lens may satisfy 0.3<f2/f<1.5.

f, an overall focal length of the optical system and, TTL, a distancefrom the object-side surface of the first lens to the imaging plane maysatisfy TTL/f<1.5.

f, an overall focal length of the optical system and, r11, a radius ofcurvature of an image-side surface of the fifth lens may satisfy1.0<r11/f.

The second lens has a positive refractive power.

The fourth lens has a positive refractive power.

In accordance with an embodiment, there is provided an optical system,including: a first lens including a negative refractive power and aconvex object-side surface; a second lens including a convex object-sidesurface and a convex image-side surface; a third lens; a fourth lensincluding a concave object-side surface; a fifth lens including anegative refractive power; and a sixth lens may include an inflectionpoint formed on an image-side surface thereof, wherein the first tosixth lenses are sequentially disposed from an object toward an imagingplane.

The first lens may include a concave image-side surface.

The third lens may include a convex object-side surface and a concaveimage-side surface.

The third lens may have a negative refractive power.

The fourth lens may include a convex image-side surface.

The fourth lens may have a positive refractive power.

The fifth lens may include a concave image-side surface.

The sixth lens may include a convex object-side surface and theimage-side surface thereof is concave.

The sixth lens has a negative refractive power.

In accordance with another embodiment, there is provided an opticalsystem, including: a first lens including a convex object-side surfaceand a concave image-side surface; a second lens including a convexobject-side surface and a convex image-side surface; a third lensincluding a convex object-side surface and a concave image-side surface;a fourth lens including a concave object-side surface and a conveximage-side surface; a fifth lens including a concave object-side surfaceand a concave image-side surface; and a sixth lens, wherein the secondlens has a same refractive power as a refractive power of the firstlens, the third lens, the fourth lens, and the fifth lens have arefractive power higher than the refractive powers of the first andsecond lenses, and the sixth lens has a refractive power lower than therefractive powers of the first and second lenses.

f, an overall focal length of the optical system and, f1, a focal lengthof the first lens may satisfy f1/f<0.

f, an overall focal length of the optical system, and r7 a radius ofcurvature of the image-side surface of the third lens may satisfy0.3<r7/f<1.4.

FOV, a field of view of the optical system may satisfy 74<FOV.

Upper and lower ends of the fifth lens extend horizontally towards anobject side, parallel to upper and lower portions of the first throughfourth lenses.

The object-side surface of the fifth lens is concave in a paraxialregion and gradually flattens at edge portions thereof.

The first lens may include a negative refractive power, the second lensmay include a positive refractive power, the third lens may include anegative refractive power, the fourth lens may include a positiverefractive power, the fifth lens may include a negative refractivepower, and the sixth lens may include a negative refractive power.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a view of an optical system, according to a first embodiment;

FIG. 2 illustrates graphs having curves representing aberration of theoptical system according to the first embodiment;

FIG. 3 is a table representing characteristics of the optical systemaccording to the first embodiment;

FIG. 4 is a table representing aspherical characteristics of the opticalsystem, according to the first embodiment;

FIG. 5 is a view of an optical system, according to a second embodiment;

FIG. 6 illustrates graphs having curves representing aberration of theoptical system, according to the second embodiment;

FIG. 7 is a table representing characteristics of the optical system,according to the second embodiment;

FIG. 8 is a table representing aspherical characteristics of the opticalsystem, according to the second embodiment;

FIG. 9 is a view of an optical system, according to a third embodiment;

FIG. 10 illustrates graphs having curves representing aberration of theoptical system, according to the third embodiment;

FIG. 11 is a table representing characteristics of the optical system,according to the third embodiment;

FIG. 12 is a table representing aspherical characteristics of theoptical system, according to the third embodiment;

FIG. 13 is a view of an optical system, according to a fourthembodiment;

FIG. 14 illustrates graphs having curves representing aberration of theoptical system, according to the fourth embodiment;

FIG. 15 is a table representing characteristics of the optical system,according to the fourth embodiment;

FIG. 16 is a table representing aspherical characteristics of theoptical system, according to the fourth embodiment;

FIG. 17 is a view of an optical system, according to a fifth embodiment;

FIG. 18 illustrates graphs having curves representing aberration of theoptical system, according to the fifth embodiment;

FIG. 19 is a table representing characteristics of the optical system,according to the fifth embodiment;

FIG. 20 is a table representing aspherical characteristics of theoptical system, according to the fifth embodiment;

FIG. 21 is a view of an optical system, according to a sixth embodiment;

FIG. 22 illustrates graphs having curves representing aberration of theoptical system, according to the sixth embodiment;

FIG. 23 is a table representing characteristics of the optical system,according to the sixth embodiment; and

FIG. 24 is a table representing aspherical characteristics of theoptical system, according to the sixth embodiment.

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals will be understood torefer to the same elements, features, and structures. The relative sizeand depiction of these elements may be exaggerated for clarity,illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent to one of ordinary skill inthe art. The sequences of operations described herein are merelyexamples, and are not limited to those set forth herein, but may bechanged as will be apparent to one of ordinary skill in the art, withthe exception of operations necessarily occurring in a certain order.Also, descriptions of functions and constructions that are well known toone of ordinary skill in the art may be omitted for increased clarityand conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various lenses, these lenses shouldnot be limited by these terms. These terms are only used to distinguishone lens from another lens. These terms do not necessarily imply aspecific order or arrangement of the lenses. Thus, a first lensdiscussed below could be termed a second lens without departing from theteachings description of the various embodiments.

Example embodiments of the present disclosure will now be described indetail with reference to the accompanying drawings.

In addition, a surface of each lens closest to an object is referred toas a first surface or an object-side surface, and a surface of each lensclosest to an imaging surface is referred to as a second surface or animage-side surface. Further, all numerical values of radii of curvature,thicknesses/distances, TTLs, and other parameters of the lenses arerepresented in millimeters (mm).

A person skilled in the relevant art will appreciate that other units ofmeasurement may be used. Further, in the present specification, allradii of curvature, thicknesses, OALs (optical axis distances from thefirst surface of the first lens to the image sensor (OALs), a distanceon the optical axis between the stop and the image sensor (SLs), imageheights (IMGHs) (image heights), and black focus lengths (BFLs) (backfocus lengths) of the lenses, an overall focal length of an opticalsystem, and a focal length of each lens are indicated in millimeters(mm). Further, thicknesses of lenses, gaps between the lenses, OALs, andSLs are distances measured based on an optical axis of the lenses.

In addition, in an embodiment, shapes of lenses are described andillustrated in relation to optical axis portions of the lenses.

A surface of a lens being convex means that an optical axis portion of acorresponding surface is convex, and a surface of a lens being concavemeans that an optical axis portion of a corresponding surface isconcave. Therefore, in a configuration in which one surface of a lens isdescribed as being convex, an edge portion of the lens may be concave.Likewise, in a configuration in which one surface of a lens is describedas being concave, an edge portion of the lens may be convex. In otherwords, a paraxial region of a lens may be convex, while the remainingportion of the lens outside the paraxial region is either convex,concave, or flat. Further, a paraxial region of a lens may be concave,while the remaining portion of the lens outside the paraxial region iseither convex, concave, or flat.

In addition, in an embodiment, thicknesses and radii of curvatures oflenses are measured in relation to optical axes of the correspondinglenses.

An optical system, according to an embodiment, includes six lenses. Asan example, the optical system may include a first lens, a second lens,a third lens, a fourth lens, a fifth lens, and a sixth lens. The lensmodule may include from four lenses up to six lenses without departingfrom the scope of the embodiments herein described. In accordance withan illustrative example, the embodiments described of the optical systeminclude six lenses with a refractive power. However, a person ofordinary skill in the relevant art will appreciate that the number oflenses in the optical system may vary, for example, between two to sixlenses, while achieving the various results and benefits describedhereinbelow. Also, although each lens is described with a particularrefractive power, a different refractive power for at least one of thelenses may be used to achieve the intended result.

In the optical system, according to embodiments, the first to sixthlenses are formed of materials including glass, plastic or other similartypes of polycarbonate materials. In another embodiment, at least one ofthe first through sixth lenses is formed of a material different fromthe materials forming the other first through sixth lenses.

The first lens has a refractive power. As an example, the first lens hasa negative refractive power. An object-side surface of the first lens isconvex. The first lens has an aspherical surface. As an example, both ofthe object-side surface and an image-side surface of the first lens areaspherical. The first lens is formed of plastic. However, a material ofthe first lens is not limited to plastic.

The second lens has a refractive power, such as a positive refractivepower or a negative refractive power. Both of an object-side surface andan image-side surface of the second lens are convex. The second lens hasan aspherical surface. As an example, both of the object-side surfaceand the image-side surface of the second lens are aspherical. The secondlens is formed of plastic. However, a material of the second lens is notlimited to plastic.

The third lens has a refractive power. As an example, the third lens mayhave negative refractive power. An object-side surface of the third lensis convex. The third lens has an aspherical surface. As an example, bothof the object-side surface and an image-side surface of the third lensare aspherical. The third lens is formed of plastic. However, a materialof the third lens is not limited to plastic.

The fourth lens may have refractive power, such as a positive refractivepower or a negative refractive power. An object-side surface of thefourth lens is concave. The fourth lens has an aspherical surface. As anexample, both of an object-side surface and the image-side surface ofthe fourth lens are aspherical. The fourth lens is formed of plastic.However, a material of the fourth lens is not limited to plastic.

The fifth lens has a refractive power. As an example, the fifth lens hasa negative refractive power. An image-side surface of the fifth lens isconcave. The fifth lens has an aspherical surface. As an example, bothof an object-side surface and the image-side surface of the fifth lensis aspherical. The fifth lens has an inflection point. As an example,one or more inflection points are formed on the image-side surface ofthe fifth lens. The fifth lens is formed of plastic. However, a materialof the fifth lens is not limited to plastic.

The sixth lens has a refractive power. As an example, the sixth lens hasa negative refractive power. An image-side surface of the sixth lens isconcave. The sixth lens has an aspherical surface. As an example, bothof an object-side surface and the image-side surface of the sixth lensare aspherical. The sixth lens has an inflection point. As an example,one or more inflection points are formed on the image-side surface ofthe sixth lens. The sixth lens is formed of plastic. However, a materialof the sixth lens is not limited to plastic.

A person of ordinary skill in the relevant art will appreciate that eachof the first through six lenses may be configured in an oppositerefractive power from the configuration described above. For example, inan alternative configuration, the first lens has a positive refractivepower, the second lens has a negative refractive power, the third lenshas a positive refractive power, the fourth lens has a negativerefractive power, the fifth lens has a positive refractive power, andthe sixth lens has a positive refractive power.

The optical system includes a filter and an image sensor. The filter isdisposed between the sixth lens and the image sensor. The filter mayfilter an infrared component from incident light refracted through thefirst to sixth lenses. The image sensor is disposed behind the filter,and converts the incident light refracted through the first to sixthlenses into electrical signals.

The optical system includes a stop. The stop adjusts an amount of lightincident to the first to sixth lenses. As an example, the stop isdisposed between the second lens and the third lens to adjust an amountto incident light.

The optical system satisfies the following Conditional Expression 1:f1/f<0.  [Conditional Expression 1]

In an example, f is an overall focal length of the optical system, andf1 is a focal length of the first lens. The Conditional Expression 1represents or defines a condition for limiting a magnitude of refractivepower of the first lens to overall refractive power of the opticalsystem. As an example, in a case in which f1/f is outside of an upperlimit value of the Conditional Expression 1, the first lens may notmaintain the negative refractive power.

The optical system satisfies one or more of the following ConditionalExpressions 2 through 4:V1 −V2<25  [Conditional Expression 2]25<V1 −V3<45  [Conditional Expression 3]25<V1 −V5<45.  [Conditional Expression 4]

In one embodiment, V1 is an Abbe number of the first lens, V2 is an Abbenumber of the second lens, V3 is an Abbe number of the third lens, andV5 is an Abbe number of the fifth lens. The Conditional Expressions 2through 4 indicate limit conditions for correction chromatic aberrationof the optical system. As an example, in a case in which V1-V2, V1-V3,and V1-V5 are outside of numerical ranges of the Conditional Expressions2 through 4, respectively, the optical system has significantly greatchromatic aberration, in such a manner that it is difficult to use theoptical system in a camera module that needs high resolution.

The optical system satisfies the following Conditional Expression 5:0.3<f2/f<1.5.  [Conditional Expression 5]

In an example, f is the overall focal length of the optical system, andf2 is a focal length of the second lens. The Conditional Expression 5represents or defines a condition for limiting a magnitude of refractivepower of the second lens to the overall refractive power of the opticalsystem. As an example, in a case in which f2/f is outside of a lowerlimit value of the Conditional Expression 5, the second lens hassignificantly great refractive power, in such a manner that it isdifficult to correct spherical aberration. As another example, in a casein which f2/f is outside of an upper limit value of the ConditionalExpression 5, the second lens has significantly low refractive power,which is advantageous to correct spherical aberration, but makesminiaturization of the optical system difficult.

The optical system satisfies the following Conditional Expression 6:−3.0<f3/f<−1.0.  [Conditional Expression 6]

In one example, f is the overall focal length of the optical system, andf3 is a focal length of the third lens. The Conditional Expressionrepresents or defines a condition for limiting a magnitude of refractivepower of the third lens to the overall refractive power of the opticalsystem. As an example, in a case in which f3/f is outside of a lowerlimit value of the Conditional Expression 6, the third lens hassignificantly great refractive power making it difficult to correctspherical aberration. As another example, in a case in which f3/f isoutside of an upper limit value of the Conditional Expression 6, thethird lens has significantly low refractive power, which is advantageousin correcting spherical aberration, but makes miniaturization of theoptical system difficult.

The optical system satisfies the following Conditional Expression 7:3.0<|f4/f|.  [Conditional Expression 7]

In an embodiment, f is the overall focal length of the optical system,and f4 is a focal length of the fourth lens. The Conditional Expression7 represents or defines a condition for limiting a magnitude ofrefractive power of the fourth lens to the overall refractive power ofthe optical system. As an example, in a case in which f4/f is outside ofa lower limit value of the Conditional Expression 7, the fourth lens hassignificantly great refractive power making it difficult to correctspherical aberration.

The optical system satisfies the following Conditional Expression 8:f5/f<−10.  [Conditional Expression 8]

In one example, f is the overall focal length of the optical system, andf5 is a focal length of the fifth lens. The Conditional Expression 8represents or defines a condition for limiting a magnitude of refractivepower of the fifth lens to the overall refractive power of the opticalsystem. As an example, in a case in which f5/f is outside of an upperlimit value of the Conditional Expression 8, the fifth lens hassignificantly great refractive power making it difficult to correctspherical aberration.

The optical system satisfies the following Conditional Expression 9:TTL/f<1.5.  [Conditional Expression 9]

In an example, f is the overall focal length of the optical system, andTTL is a distance from the object-side surface of the first lens to animaging plane. The Conditional Expression 9 represents or defines acondition for miniaturizing the optical system. As an example, in a casein which TTL/f is outside of an upper limit value of the ConditionalExpression 9, it is difficult to mount the optical system in a smallportable terminal.

The optical system satisfies the following Conditional Expression 10:f1/f2<0.  [Conditional Expression 10]

In an embodiment, f1 is the focal length of the first lens, and f2 isthe focal length of the second lens. The Conditional Expression 10represents or defines a condition for limiting a ratio of refractivepower between the first lens and the second lens. As an example, in acase in which f1/f2 is outside of an upper limit value of theConditional Expression 10, refractive power of the first lens or thesecond lens is significantly great making it difficult to correctaberration.

The optical system satisfies the following Conditional Expression 11:−1.2<f2/f3<0.  [Conditional Expression 11]

In one example, f2 is the focal length of the second lens, and f3 is thefocal length of the third lens. The Conditional Expression 11 representsor defines a condition for limiting a ratio of refractive power betweenthe second lens and the third lens. As an example, in a case in whichf2/f3 is outside of a numerical range of the Conditional Expression 11,refractive power of the second lens or the third lens is significantlygreat making it difficult to correct aberration.

The optical system satisfies the following Conditional Expression 12:BFL/f<0.5.  [Conditional Expression 12]

In an embodiment, f is the overall focal length of the optical system,and BFL is a distance from the object-side surface of the sixth lens tothe imaging plane. The Conditional Expression 12 represents or defines acondition for miniaturizing the optical system. As an example, in a casein which BFL/f is outside of an upper limit value of the ConditionalExpression 12, it is difficult to miniaturize the optical system.

The optical system satisfies the following Conditional Expression 13:D2/f<0.1.  [Conditional Expression 13]

In one embodiment, f is the overall focal length of the optical system,and D2 is a distance from the image-side surface of the first lens tothe object-side surface of the second lens. The Conditional Expression13 represents or defines a condition for improving longitudinalchromatic aberration characteristics. As an example, in a case in whichD2/f is outside of an upper limit value of the Conditional Expression13, the first lens and the second lens may have deterioratedlongitudinal chromatic aberration characteristics.

The optical system satisfies the following Conditional Expression 14:0.3<r7/f<1.4.  [Conditional Expression 14]

In an example, f is the overall focal length of the optical system, andr7 is a radius of curvature of the image-side surface of the third lens.The Conditional Expression 14 represents or defines a condition forlimiting refractive power of the third lens. As an example, in a case inwhich r7/f is outside of a numerical range of the Conditional Expression14, it is not easy to manufacture the third lens, and it is difficult tosecure the required refractive power.

The optical system satisfies the following Conditional Expression 15:1.0<r11/f.  [Conditional Expression 15]

In one example, f is the overall focal length of the optical system, andr11 is a radius of curvature of the image-side surface of the fifthlens. The Conditional Expression 15 represents or defines a conditionfor limiting refractive power of the fifth lens. As an example, in acase in which r11/f is outside of a numerical range of the ConditionalExpression 15, it is not easy to manufacture the fifth lens, and it isdifficult to secure the required refractive power.

The optical system satisfies one or more of the following ConditionalExpressions 16 and 17:74<FOV  [Conditional Expression 16]F number<2.1.  [Conditional Expression 17]

In a further example, FOV is a field of view of the optical system.

The optical system configured as described above realizes a cameramodule having a wide field of view and high resolution.

Also, in one embodiment, each of the first to sixth lenses may beseparate lenses configured as described above. A distance between lensesmay vary. In another embodiment, at least one of the first to sixthlenses may be operatively connected or in contact with another one ofthe first to sixth lenses.

In a further alternative embodiment, two or more of the lenses of thefirst to sixth lenses may be configured as a group and in operativeconnection or contact with another lens. For instance, the first,second, and third lenses may be in contact with each other as a firstgroup lens, while the fourth, fifth, and sixth lenses are configuredseparate from each other and from the first group lens. In thealternative, the first, second, and third lenses may be in contact witheach other as a first group lens, the fourth and the fifth lenses may bein contact with each other as a second group lens, and the sixth lens isconfigured separate from the first and second group lenses.

Next, several embodiments will be described.

An optical system, according to a first embodiment, will be describedwith reference to FIG. 1.

The optical system 100, according to an embodiment, includes first tosixth lenses 110 to 160. The first to sixth lenses 110 to 160 aresequentially disposed from an object toward an imaging plane.

The first lens 110 has a negative refractive power. An object-sidesurface of the first lens 110 is convex, and an image-side surfacethereof is concave. The first lens 110 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe first lens 110 are aspherical. The first lens 110 may be formed of amaterial having a refractive index of 1.547. A focal length of the firstlens 110 may be −47457.1 mm.

The second lens 120 has a positive refractive power. An object-sidesurface of the second lens 120 is convex, and an image-side surfacethereof is convex. The second lens 120 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe second lens 120 are aspherical. The second lens 120 is formed of amaterial that is substantially the same as or similar to that of thefirst lens. As an example, the second lens 120 has a refractive index of1.547, which is the same as that of the first lens. A focal length ofthe second lens 120 may be 2.788 mm.

The third lens 130 has a negative refractive power. An object-sidesurface of the third lens 130 is convex, and an image-side surfacethereof is concave. The third lens 130 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe third lens 130 are aspherical. The third lens 130 has a refractiveindex higher than the refractive powers of the first and second lenses.As an example, a refractive index of the third lens 130 may be 1.657,which is higher than the refractive indices of the first and secondlenses. A focal length of the third lens 130 may be −5.794 mm.

The fourth lens 140 has a positive refractive power. An object-sidesurface of the fourth lens 140 is concave, and an image-side surfacethereof is convex. The fourth lens 140 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fourth lens 140 are aspherical. The fourth lens 140 has a refractiveindex higher than the refractive indices of the first and second lenses.As an example, a refractive index of the fourth lens 140 may be 1.657,which is higher than the refractive indices of the first and secondlenses. A focal length of the fourth lens 140 may be 158.832 mm.

The fifth lens 150 has a negative refractive power. An object-sidesurface of the fifth lens 150 is convex, and an image-side surfacethereof is concave. The fifth lens 150 has an aspherical shape. Forexample, the object-side surface of the fifth lens 150 is convex in theparaxial region, and the image-side surface of the fifth lens 150 isconcave in the paraxial region. As an example, both of the object-sidesurface and the image-side surface of the fifth lens 150 are aspherical.An inflection point is formed on the fifth lens 150. As an example, oneor more inflection points are formed on the image-side surface of thefifth lens 150. The fifth lens 150 has a refractive index higher thanthe refractive indices of the first and second lenses. As an example, arefractive index of the fifth lens 150 may be 1.657, which is higherthan the refractive indices of the first and second lenses. A focallength of the fifth lens 150 may be −176353.3 mm.

The sixth lens 160 has a negative refractive power. An object-sidesurface of the sixth lens 160 is convex, and an image-side surfacethereof is concave. The sixth lens 160 may have an aspherical shape. Forexample, the object-side surface of the sixth lens 16 is convex in theparaxial region, and the image-side surface of the sixth lens 160 isconcave in the paraxial region. As an example, both of the object-sidesurface and the image-side surface of the sixth lens 160 are aspherical.An inflection point is formed on the sixth lens 160. As an example, oneor more inflection points are formed on the object-side surface and theimage-side surface of the sixth lens 160. The sixth lens 160 has a lowrefractive index. As an example, a refractive index of the sixth lens160 may be 1.537, which is lower than the refractive indices of thefirst and second lenses. A focal length of the sixth lens 160 may be−13.349 mm.

The optical system 100 includes a filter 170 and an image sensor 180.The filter 170 is disposed adjacently to the image-side surface of thesixth lens 160. The filter 170 has a substantially flat plate. Thefilter 170 filters infrared rays from light refracted from the sixthlens 160.

The image sensor 180 is disposed behind the filter 170. The image sensor180 has a predetermined size. As an example, a distance (IMH HT) (seeFIG. 2) from an intersection point between an imaging plane of the imagesensor 180 and an optical axis to a diagonal corner of the image sensor180 may be 3.50 mm.

The optical system 100 includes a stop STOP. The stop STOP is disposedbetween the second lens and the third lens. However, a person skill inthe art will appreciate that the stop ST may be positioned in betweentwo of the lenses 110 to 160.

The optical system 100 configured as described above representsaberration characteristics and optical characteristics as illustrated inFIGS. 2 and 3. As an example, an F number of the optical system 100,according to an embodiment, is 2.09, an overall length (TTL), which is adistance from the object-side surface of the first lens to the imagingplane of the optical system 100, is 5.211 mm, and an overall focallength of the optical system 100 is 4.492 mm. For reference, FIG. 4 is atable representing aspherical coefficients of the optical system 100.

An optical system, according to a second embodiment, will be describedwith reference to FIG. 5.

The optical system 200, according to an embodiment, includes first tosixth lenses 210 to 260. The first to sixth lenses 210 to 260 aresequentially disposed from an object toward an imaging plane.

The first lens 210 has a negative refractive power. An object-sidesurface of the first lens 210 is convex, and an image-side surfacethereof is concave. The first lens 210 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe first lens 210 are aspherical. The first lens 210 may be formed of amaterial having a refractive index of 1.547. A focal length of the firstlens 210 may be −40047.4 mm.

The second lens 220 has a positive refractive power. An object-sidesurface of the second lens 220 is convex, and an image-side surfacethereof is convex. The second lens 220 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe second lens 220 are aspherical. The second lens 220 is formed of amaterial that is substantially the same as or similar to that of thefirst lens. As an example, the second lens 220 has a refractive index of1.547, which is the same as that of the first lens. A focal length ofthe second lens 220 may be 2.780 mm.

The third lens 230 has a negative refractive power. An object-sidesurface of the third lens 230 is convex, and an image-side surfacethereof is concave. The third lens 230 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe third lens 230 are aspherical. The third lens 230 has a refractiveindex higher than the refractive indices of the first and second lenses.As an example, a refractive index of the third lens 230 may be 1.657,which is higher than the refractive indices of the first and secondlenses. A focal length of the third lens 230 may be −5.758 mm.

The fourth lens 240 has a positive refractive power. An object-sidesurface of the fourth lens 240 is concave, and an image-side surfacethereof is convex. The fourth lens 240 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fourth lens 240 are aspherical. The fourth lens 240 has a refractiveindex higher than the refractive indices of the first and second lenses.As an example, refractive index of the fourth lens 240 may be 1.657,which is higher than the refractive indices of the first and secondlenses. A focal length of the fourth lens 240 may be 69.588 mm.

The fifth lens 250 has a negative refractive power. An object-sidesurface of the fifth lens 250 is convex, and an image-side surfacethereof is concave. The fifth lens 250 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fifth lens 250 are aspherical. An inflection point is formed on thefifth lens 250. As an example, one or more inflection points may beformed on the image-side surface of the fifth lens 250. The fifth lens250 has a refractive index higher than the refractive indices of thefirst and second lenses. As an example, a refractive index of the fifthlens 250 may be 1.657, which is higher than the refractive indices ofthe first and second lenses. A focal length of the fifth lens 250 may be−405.09 mm. In accordance with an embodiment, as shown in FIG. 5, upperand lower ends of the fifth lens 250 extend horizontally towards theobject side, parallel to upper and lower portions of the first throughfourth lenses 210 through 240, without contacting the upper and lowerportions of the first through fourth lenses 210 through 240.

The sixth lens 260 has a negative refractive power. An object-sidesurface of the sixth lens 260 is convex, and an image-side surfacethereof is concave. The sixth lens 260 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe sixth lens 260 are aspherical. An inflection point is formed on thesixth lens 260. As an example, one or more inflection points are formedon the object-side surface and the image-side surface of the sixth lens260. The sixth lens 260 has a low refractive index. As an example, arefractive index of the sixth lens 260 may be 1.537, which is lower thanthe refractive indices of the first and second lenses. A focal length ofthe sixth lens 260 may be −13.722 mm.

The optical system 200 includes a filter 270 and an image sensor 280.The filter 270 is disposed adjacently to the image-side surface of thesixth lens 260. The filter 270 has a substantially flat plate. Thefilter 270 filters infrared rays from light refracted from the sixthlens 260.

The image sensor 280 is disposed behind the filter 270. The image sensor280 has a predetermined size. As an example, a distance (IMH HT) (seeFIG. 2) from an intersection point between an imaging plane of the imagesensor 280 and an optical axis to a diagonal corner of the image sensor280 is 3.50 mm.

The optical system 200 includes a stop STOP. The stop STOP is disposedbetween the second lens and the third lens.

The optical system 200 configured as described above may representaberration characteristics and optical characteristics as illustrated inFIGS. 6 and 7. As an example, an F number of the optical system 200,according to an embodiment may be 2.07, an overall length (TTL), whichis a distance from the object-side surface of the first lens to theimaging plane of the optical system 200, is 5.104 mm, and an overallfocal length of the optical system 200 is 4.402 mm. For reference, FIG.8 is a table representing aspherical coefficients of the optical system200.

An optical system, according to a third embodiment, will be describedwith reference to FIG. 9.

The optical system 300, according to an embodiment, includes first tosixth lenses 310 to 360. The first to sixth lenses 310 to 360 aresequentially disposed from an object toward an imaging plane.

The first lens 310 has a negative refractive power. An object-sidesurface of the first lens 310 is convex, and an image-side surfacethereof is concave. The first lens 310 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe first lens 310 are aspherical. The first lens 310 may be formed of amaterial having a refractive index of 1.547. A focal length of the firstlens 310 may be −95.513 mm.

The second lens 320 has a positive refractive power. An object-sidesurface of the second lens 320 is convex, and an image-side surfacethereof is convex. The second lens 320 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe second lens 320 are aspherical. The second lens 320 is formed of amaterial that is substantially the same as or similar to that of thefirst lens. As an example, the second lens 320 has a refractive index of1.547, which is the same as that of the first lens. A focal length ofthe second lens 320 may be 2.716 mm.

The third lens 330 has a negative refractive power. An object-sidesurface of the third lens 330 is convex, and an image-side surfacethereof is concave. The third lens 330 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe third lens 330 are aspherical. The third lens 330 has a refractiveindex higher than the refractive indices of the first and second lenses.As an example, a refractive index of the third lens 330 is 1.657, whichis higher than the refractive indices of the first and second lenses. Afocal length of the third lens 330 may be −6.192 mm.

The fourth lens 340 has a positive refractive power. An object-sidesurface of the fourth lens 340 is concave, and an image-side surfacethereof is convex. The fourth lens 340 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fourth lens 340 are aspherical. The fourth lens 340 may have arefractive index higher than the refractive indices of the first andsecond lenses. As an example, a refractive index of the fourth lens 340is 1.657, which is higher than the refractive indices of the first andsecond lenses. A focal length of the fourth lens 340 may be 62.408 mm.

The fifth lens 350 has a negative refractive power. An object-sidesurface of the fifth lens 350 is concave, and an image-side surfacethereof is concave. The fifth lens 350 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fifth lens 350 are aspherical. An inflection point is formed on thefifth lens 350. As an example, one or more inflection points are formedon the image-side surface of the fifth lens 350. The fifth lens 350 hasa refractive index higher than the refractive indices of the first andsecond lenses. As an example, a refractive index of the fifth lens 350may be 1.657, which is higher than the refractive indices of the firstand second lenses. A focal length of the fifth lens 350 may be −196.150mm. In one example, the object-side surface of the fifth lens 350 isconcave in a paraxial region and gradually flattens at edge portionsthereof.

The sixth lens 360 has a negative refractive power. An object-sidesurface of the sixth lens 360 is convex, and an image-side surfacethereof is concave. The sixth lens 360 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe sixth lens 360 are aspherical. An inflection point is formed on thesixth lens 360. As an example, one or more inflection points are formedon the object-side surface and the image-side surface of the sixth lens360. The sixth lens 360 has a low refractive index. As an example,refractive power of the sixth lens 360 may be 1.537, which is lower thanthe refractive indices of the first and second lenses. A focal length ofthe sixth lens 360 may be −11.896 mm.

The optical system 300 includes a filter 370 and an image sensor 380.The filter 370 is disposed adjacently to the image-side surface of thesixth lens 360. The filter 370 has a substantially flat plate. Thefilter 370 filters an infrared ray from light refracted from the sixthlens 360.

The image sensor 380 is disposed behind the filter 370. The image sensor380 has a predetermined size. As an example, a distance (IMH HT) (seeFIG. 2) from an intersection point between an imaging plane of the imagesensor 380 and an optical axis to a diagonal corner of the image sensor380 may be 3.50 mm.

The optical system 300 includes a stop STOP. The stop STOP is disposedbetween the second lens and the third lens.

The optical system 300 configured as described above may representaberration characteristics and optical characteristics as illustrated inFIGS. 10 and 11. As an example, an F number of the optical system 300,according an embodiment, is 2.09, an overall length (TTL), which is adistance from the object-side surface of the first lens to the imagingplane of the optical system 300, is 5.104 mm, and an overall focallength of the optical system 300 is 4.392 mm. For reference, FIG. 12 isa table representing aspherical coefficients of the optical system 300.

An optical system, according to a fourth embodiment, will be describedwith reference to FIG. 13.

The optical system 400, according to an embodiment, includes first tosixth lenses 410 to 460. The first to sixth lenses 410 to 460 aresequentially disposed from an object toward an imaging plane.

The first lens 410 has a negative refractive power. An object-sidesurface of the first lens 410 is convex, and an image-side surfacethereof is concave. The first lens 410 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe first lens 410 are aspherical. The first lens 410 may be formed of amaterial having a refractive index of 1.547. A focal length of the firstlens 410 may be −677.554 mm.

The second lens 420 has a positive refractive power. An object-sidesurface of the second lens 420 is convex, and an image-side surfacethereof is convex. The second lens 420 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe second lens 420 are aspherical. The second lens 420 is formed of amaterial that is substantially the same as or similar to that of thefirst lens. As an example, the second lens 420 has a refractive index of1.547, which is the same as that of the first lens. A focal length ofthe second lens 420 may be 2.800 mm.

The third lens 430 has a negative refractive power. An object-sidesurface of the third lens 430 is convex, and an image-side surfacethereof is concave. The third lens 430 may have an aspherical shape. Asan example, both of the object-side surface and the image-side surfaceof the third lens 430 may be aspherical. The third lens 430 has arefractive index higher than the refractive indices of the first andsecond lenses. As an example, a refractive index of the third lens 430may be 1.657, which is higher than the refractive indices of the firstand second lenses. A focal length of the third lens 430 may be −5.988mm.

The fourth lens 440 has a positive refractive power. An object-sidesurface of the fourth lens 440 is concave, and an image-side surfacethereof is convex. The fourth lens 440 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fourth lens 440 are aspherical. The fourth lens 440 has a refractiveindex higher than the refractive indices of the first and second lenses.As an example, a refractive index of the fourth lens 440 is 1.657, whichis higher than the refractive indices of the first and second lenses. Afocal length of the fourth lens 440 may be 31.426 mm.

The fifth lens 450 has a negative refractive power. An object-sidesurface of the fifth lens 450 is concave, and an image-side surfacethereof is concave. The fifth lens 450 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fifth lens 450 are aspherical. An inflection point is formed on thefifth lens 450. As an example, one or more inflection points are formedon the image-side surface of the fifth lens 450. The fifth lens 450 hasa refractive index higher than the refractive indices of the first andsecond lenses. As an example, a refractive index of the fifth lens 450may be 1.657, which is higher than the refractive indices of the firstand second lenses. A focal length of the fifth lens 450 may be −80.848mm. In one example, the object-side surface of the fifth lens 450 isconcave in a paraxial region and gradually flattens at edge portionsthereof

The sixth lens 460 has a negative refractive power. An object-sidesurface of the sixth lens 460 is convex, and an image-side surfacethereof is concave. The sixth lens 460 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe sixth lens 460 are aspherical. An inflection point is formed on thesixth lens 460. As an example, one or more inflection points are formedon the object-side surface and the image-side surface of the sixth lens460. The sixth lens 460 has a low refractive index. As an example, arefractive index of the sixth lens 460 may be 1.537, which is lower thanthe refractive indices of the first and second lenses. A focal length ofthe sixth lens 460 may be −10.783 mm.

The optical system 400 includes a filter 470 and an image sensor 480.The filter 470 is disposed adjacently to the image-side surface of thesixth lens 460. The filter 470 has a substantially flat plate. Thefilter 470 filters infrared rays from light refracted from the sixthlens 460.

The image sensor 480 is disposed behind the filter 470. The image sensor480 has a predetermined size. As an example, a distance (IMH HT) (seeFIG. 2) from an intersection point between an imaging plane of the imagesensor 480 and an optical axis to a diagonal corner of the image sensor480 is 3.50 mm.

The optical system 400 includes a stop STOP. The stop STOP is disposedbetween the second lens and the third lens.

The optical system 400 configured as described above may representaberration characteristics and optical characteristics as illustrated inFIGS. 14 and 15. As an example, an F number of the optical system 400,according to an embodiment is 2.00, an overall length (TTL), which is adistance from the object-side surface of the first lens to the imagingplane of the optical system 400, is 5.103 mm, and an overall focallength of the optical system 400 is 4.327 mm. For reference, FIG. 16 isa table representing aspherical coefficients of the optical system 400.

An optical system, according to a fifth embodiment, will be describedwith reference to FIG. 17.

The optical system 500, according to an embodiment, includes first tosixth lenses 510 to 560. The first to sixth lenses 510 to 560 aresequentially disposed from an object toward an imaging plane.

The first lens 510 has a negative refractive power. An object-sidesurface of the first lens 510 is convex, and an image-side surfacethereof is concave. The first lens 510 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe first lens 510 are aspherical. The first lens 510 is formed of amaterial having a refractive index of 1.547. A focal length of the firstlens 510 may be −9275.74 mm.

The second lens 520 has a positive refractive power. An object-sidesurface of the second lens 520 is convex, and an image-side surfacethereof is convex. The second lens 520 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe second lens 520 re aspherical. The second lens 520 is formed of amaterial that is substantially the same as or similar to that of thefirst lens. As an example, the second lens 520 has a refractive index of1.547, which is the same as that of the first lens. A focal length ofthe second lens 520 may be 2.816 mm.

The third lens 530 has a negative refractive power. An object-sidesurface of the third lens 530 is convex, and an image-side surfacethereof is concave. The third lens 530 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe third lens 530 are aspherical. The third lens 530 has a refractiveindex higher than the refractive indices of the first and second lenses.As an example, a refractive index of the third lens 530 may be 1.657,which is higher than the refractive indices of the first and secondlenses. A focal length of the third lens 530 may be −6.016 mm.

The fourth lens 540 has a positive refractive power. An object-sidesurface of the fourth lens 540 is concave, and an image-side surfacethereof is convex. The fourth lens 540 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fourth lens 540 are aspherical. The fourth lens 540 has a refractiveindex higher than the refractive indices of the first and second lenses.As an example, a refractive index of the fourth lens 540 is 1.657, whichis higher than the refractive indices of the first and second lenses. Afocal length of the fourth lens 540 may be 30.800 mm.

The fifth lens 550 has a negative refractive power. An object-sidesurface of the fifth lens 550 is concave, and an image-side surfacethereof is concave. The fifth lens 550 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fifth lens 550 are aspherical. An inflection point is formed on thefifth lens 550. As an example, one or more inflection points are formedon the image-side surface of the fifth lens 550. The fifth lens 550 hasa refractive index higher than the refractive indices of the first andsecond lenses. As an example, a refractive index of the fifth lens 550may be 1.657, which is higher than the refractive indices of the firstand second lenses. A focal length of the fifth lens 550 may be −68.976mm. In one example, the object-side surface of the fifth lens 550 isconcave in a paraxial region and gradually flattens at edge portionsthereof.

The sixth lens 560 has a negative refractive power. An object-sidesurface of the sixth lens 560 is convex, and an image-side surfacethereof may be concave. The sixth lens 560 may have an aspherical shape.As an example, both of the object-side surface and the image-sidesurface of the sixth lens 560 are aspherical. An inflection point isformed on the sixth lens 560. As an example, one or more inflectionpoints are formed on the object-side surface and the image-side surfaceof the sixth lens 560. The sixth lens 560 has a low refractive index. Asan example, a refractive index of the sixth lens 560 may be 1.537, whichis lower than the refractive indices of the first and second lenses. Afocal length of the sixth lens 560 may be −11.437 mm.

The optical system 500 includes a filter 570 and an image sensor 580.The filter 570 is disposed adjacently to the image-side surface of thesixth lens 560. The filter 570 has a substantially flat plate. Thefilter 570 filters infrared rays from light refracted from the sixthlens 560.

The image sensor 580 is disposed behind the filter 570. The image sensor580 has a predetermined size. As an example, a distance (IMH HT) (seeFIG. 2) from an intersection point between an imaging plane of the imagesensor 580 and an optical axis to a diagonal corner of the image sensor580 is 3.50 mm.

The optical system 500 includes a stop STOP. The stop STOP is disposedbetween the second lens and the third lens.

The optical system 500 configured as described above representsaberration characteristics and optical characteristics as illustrated inFIGS. 18 and 19. As an example, an F number of the optical system 500,according to an embodiment, is 1.98, an overall length (TTL), which is adistance from the object-side surface of the first lens to the imagingplane) of the optical system 500, is 5.102 mm, and an overall focallength of the optical system 500 is 4.303 mm. For reference, FIG. 20 isa table representing aspherical coefficients of the optical system 500.

An optical system, according to a sixth embodiment, will be describedwith reference to FIG. 21.

The optical system 600, according to an embodiment, includes first tosixth lenses 610 to 660. The first to sixth lenses 610 to 660 may besequentially disposed from an object toward an imaging plane.

The first lens 610 has a negative refractive power. An object-sidesurface of the first lens 610 is convex, and an image-side surfacethereof is concave. The first lens 610 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe first lens 610 are aspherical. The first lens 610 may be formed of amaterial having a refractive index of 1.547. A focal length of the firstlens 610 may be −5064.53 mm.

The second lens 620 has a positive refractive power. An object-sidesurface of the second lens 320 is convex, and an image-side surfacethereof is convex. The second lens 620 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe second lens 620 are aspherical. The second lens 620 is formed of amaterial that is substantially the same as or similar to that of thefirst lens. As an example, the second lens 620 has a refractive index of1.547, which is the same as that of the first lens. A focal length ofthe second lens 620 may be 2.818 mm.

The third lens 630 has a negative refractive power. An object-sidesurface of the third lens 630 is convex, and an image-side surfacethereof is concave. The third lens 630 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe third lens 630 are aspherical. The third lens 630 has a refractiveindex higher than the refractive indices of the first and second lenses.As an example, a refractive index of the third lens 630 is 1.657, whichis higher than the refractive indices of the first and second lenses. Afocal length of the third lens 630 may be −5.971 mm.

The fourth lens 640 has a positive refractive power. An object-sidesurface of the fourth lens 640 is concave, and an image-side surfacethereof is convex. The fourth lens 640 may have an aspherical shape. Asan example, both of the object-side surface and the image-side surfaceof the fourth lens 640 may be aspherical. The fourth lens 640 may have arefractive index higher than the refractive indices of the first andsecond lenses. As an example, a refractive index of the fourth lens 640may be 1.657, which is higher than the refractive indices of the firstand second lenses. A focal length of the fourth lens 640 may be 29.146mm.

The fifth lens 650 has a negative refractive power. An object-sidesurface of the fifth lens 650 is concave, and an image-side surfacethereof is concave. The fifth lens 650 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe fifth lens 650 is aspherical. An inflection point is formed on thefifth lens 650. As an example, one or more inflection points is formedon the image-side surface of the fifth lens 650. The fifth lens 650 hasa refractive index higher than the refractive indices of the first andsecond lenses. As an example, a refractive index of the fifth lens 650is 1.657, which is higher than the refractive indices of the first andsecond lenses. A focal length of the fifth lens 650 may be −97.168 mm.In one example, the object-side surface of the fifth lens 650 is concavein a paraxial region and gradually flattens at edge portions thereof.

The sixth lens 660 has a negative refractive power. An object-sidesurface of the sixth lens 660 is convex, and an image-side surfacethereof is concave. The sixth lens 660 has an aspherical shape. As anexample, both of the object-side surface and the image-side surface ofthe sixth lens 660 are aspherical. An inflection point is formed on thesixth lens 660. As an example, one or more inflection points is formedon the object-side surface and the image-side surface of the sixth lens660. The sixth lens 660 has a low refractive index. As an example, arefractive index of the sixth lens 660 may be 1.537, which is lower thanthe refractive indices of the first and second lenses. A focal length ofthe sixth lens 660 may be −10.966 mm.

The optical system 600 includes a filter 670 and an image sensor 680.The filter 670 is disposed adjacently to the image-side surface of thesixth lens 660. The filter 670 has a substantially flat plate. Thefilter 670 filters infrared rays from light refracted from the sixthlens 660.

The image sensor 680 is disposed behind the filter 670. The image sensor680 has a predetermined size. As an example, a distance (IMH HT) (seeFIG. 2) from an intersection point between an imaging plane of the imagesensor 680 and an optical axis to a diagonal corner of the image sensor680 may be 3.50 mm.

The optical system 600 includes a stop STOP. The stop STOP is disposedbetween the second lens and the third lens.

The optical system 600 configured as described above, representsaberration characteristics and optical characteristics as illustrated inFIGS. 22 and 23. As an example, an F number of the optical system 600,according to an embodiment, is 1.98, an overall length (TTL), which is adistance from the object-side surface of the first lens to the imagingplane of the optical system 600, is 5.102 mm, and an overall focallength of the optical system 600 is 4.298 mm. For reference, FIG. 24 isa table representing aspherical coefficients of the optical system 600.

The optical systems, according to the first to sixth embodiments,configured as described above satisfy all of the Conditional Expressions1 through 17, as represented in Table 1.

TABLE 1 Conditional First Second Third Fourth Fifth Sixth RemarkExpression Embodiment Embodiment Embodiment Embodiment EmbodimentEmbodiment 1 f1/f < 0 −10565.046 −9096.919 −21.746 −156.580 −2155.795−1178.319 2 V1 − V2 < 25 0.0 0.0 0.0 0.0 0.0 0.0 3 25 < V1 − V3 < 4534.60 34.60 34.60 34.60 34.60 34.60 4 25 < V1 − V5 < 45 34.60 34.6034.60 34.60 34.60 34.60 5 0.3 < f2/f < 1.5 0.621 0.631 0.618 0.647 0.6540.656 6 −3.0 < f3/f < −1.0 −1.290 −1.308 −1.410 −1.384 −1.398 −1.389 73.0 < |f4/f| 35.360 15.807 14.209 7.262 7.158 6.781 8 f5/f < −10−39260.348 −92.017 −44.659 −18.684 −16.031 −22.607 9 TTL/f < 1.5 1.1601.159 1.162 1.179 1.186 1.187 10 f1/f2 < 0 −17021.600 −14405.667 −35.168−241.959 −3294.040 −1797.493 11 −1.2 < f2/f3 < 0 −0.481 −0.483 −0.439−0.468 −0.468 −0.472 12 BFL/f < 0.5 0.235 0.240 0.250 0.236 0.239 0.24113 D2/f < 0.1 0.014 0.014 0.009 0.012 0.013 0.013 14 0.3 < r7/f < 1.40.519 0.528 0.554 0.552 0.556 0.554 15 1.0 < r11/f 1.537 1.451 33.71112.975 11.042 15.879 16 74 < FOV 74.1 75.2 75.3 76.2 76.4 76.4 17 Fnumber < 2.1 2.09 2.07 2.08 2.00 1.98 1.98

As set forth above, the optical system, according to an embodiment,photographs a clear image.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. An optical system, comprising: a first lenscomprising a negative refractive power and a convex object-side surface;a second lens comprising a convex image side surface in a paraxialregion; a third lens comprising a negative refractive power and a convexobject-side surface; a fourth lens comprising a concave object sidesurface in a paraxial region; a fifth lens comprising a negativerefractive power and a concave image side surface in a paraxial region;and a sixth lens comprising a negative refractive power and comprisingan inflection point on an image-side surface thereof, wherein the firstto sixth lenses are sequentially disposed from an object toward animaging plane.
 2. The optical system of claim 1, wherein, V1, an Abbenumber of the first lens and, V3, an Abbe number of the third lenssatisfy 25<V1−V3<45.
 3. The optical system of claim 1, wherein, f, anoverall focal length of the optical system and, f2, a focal length ofthe second lens satisfy 0.3<f2/f<1.5.
 4. The optical system of claim 1,wherein, f, an overall focal length of the optical system and, TTL, adistance from the object-side surface of the first lens to the imagingplane satisfy TTL/f<1.5.
 5. The optical system of claim 1, wherein, f,an overall focal length of the optical system and, r11, a radius ofcurvature of an image-side surface of the fifth lens satisfy 1.0<r11/f.6. The optical system of claim 1, wherein the second lens has a positiverefractive power.
 7. The optical system of claim 1, wherein the fourthlens has a positive refractive power.
 8. An optical system, comprising:a first lens comprising a negative refractive power and a convexobject-side surface; a second lens comprising a convex object-sidesurface and a convex image-side surface in a paraxial region; a thirdlens having a negative refractive power; a fourth lens comprising aconcave object-side surface in a paraxial region; a fifth lenscomprising a negative refractive power; and a sixth lens comprises aninflection point formed on an image-side surface thereof, wherein thefirst to sixth lenses are sequentially disposed from an object toward animaging plane, and wherein f5/f<−10; where f5 is a focal length of thefifth lens and f is an overall focal length of the optical system. 9.The optical system of claim 8, wherein the first lens comprises aconcave image-side surface.
 10. The optical system of claim 8, whereinthe third lens comprises a convex object-side surface and a concaveimage-side surface.
 11. The optical system of claim 8, wherein thefourth lens comprises a convex image-side surface.
 12. The opticalsystem of claim 8, wherein the fourth lens has a positive refractivepower.
 13. The optical system of claim 8, wherein the fifth lenscomprises a concave image-side surface.
 14. The optical system of claim8, wherein the sixth lens comprises a convex object-side surface and theimage-side surface thereof is concave.
 15. The optical system of claim8, wherein the sixth lens has a negative refractive power.
 16. Anoptical system, comprising: a first lens comprising a convex object-sidesurface and a concave image-side surface; a second lens comprising aconvex object-side surface and a convex image-side surface in a paraxialregion; a third lens comprising a convex object-side surface and aconcave image-side surface; a fourth lens comprising a concaveobject-side surface in a paraxial region and a convex image-sidesurface; a fifth lens comprising a concave object-side surface and aconcave image-side surface in a paraxial region; and a sixth lens,wherein the second lens is formed of a material that is substantiallysame as that of the first lens, the third lens, the fourth lens, and thefifth lens each have a refractive index higher than the refractiveindices of each of the first and second lenses, and the sixth lens has arefractive index lower than the refractive indices of each of the firstand second lenses.
 17. The optical system of claim 16, wherein, f, anoverall focal length of the optical system and, f1, a focal length ofthe first lens satisfy f1/f<0.
 18. The optical system of claim 16,wherein, f, an overall focal length of the optical system, and r7 aradius of curvature of the image-side surface of the third lens satisfy0.3<r7/f<1.4.
 19. The optical system of claim 16, wherein, FOV, a fieldof view of the optical system satisfy 74<FOV.
 20. The optical system ofclaim 16, wherein upper and lower ends of the fifth lens extendhorizontally towards an object side, parallel to upper and lowerportions of the first through fourth lenses.
 21. The optical system ofclaim 16, wherein the object-side surface of the fifth lens is concavein a paraxial region and gradually flattens at edge portions thereof.22. The optical system of claim 16, wherein the first lens comprises anegative refractive power, the second lens comprises a positiverefractive power, the third lens comprises a negative refractive power,the fourth lens comprises a positive refractive power, the fifth lenscomprises a negative refractive power, and the sixth lens comprises anegative refractive power.